Move the VSync work to Screen.

The problem we're running into is entirely contained in the Screen - we need to
either decouple graphics context init from Screen::init or we need to take out
the screenbuffer interaction from loadstats (which I'm more in favor of since we
can just pull the config values and pass them to Screen::init later).

desktop_version/src/Render.cpp

@@ -231,7 +231,7 @@ void menurender()
             graphics.bigprint(-1, 30, "Toggle VSync", tr, tg, tb, true);
             graphics.Print(-1, 65, "Turn VSync on or off.", tr, tg, tb, true);
 
-            if (!graphics.vsync)
+            if (!graphics.screenbuffer->vsync)
             {
                 graphics.Print(-1, 95, "Current mode: VSYNC OFF", tr/2, tg/2, tb/2, true);
             }